The present invention relates to a signal diagnostic method and diagnostic apparatus for a multiple information transmission system, and more particularly to a signal diagnostic method and diagnostic apparatus for a multiple information transmission system which are capable of detecting the error of a signal in a short time.
In case of transmitting a large number of information to an equipment located at a remote position, a serial transmission signal-transmitting system is adopted for the purpose of reducing expenses for laying cables for information transmission. A serial transmission signal is composed of a synchronizing signal part A and an information signal part B. The synchronizing signal part A includes a synchronizing signal C and a synchronizing bit D. The serial transmission signal is transmitted as serial information which consists of the synchronizing signal part A and the information signal part B as a unit. In general, in such transmission system, a multiple transmission system with the information transmission system made redundant is adopted for enhancing the reliability of the transmitted information, and a method is adopted in which the presence or absence of an error in any transmission signal transmitted in the multiple transmission system is decided by the comparisons of the respective transmission signals.
An example of a triple information transmission system in a prior art will be described below. A measurement value obtained by a certain detector disposed in a nuclear power plant is transmitted to three juxtaposed transmitters, which convert the measurement value into serial transmission signals respectively. These signals are transmitted to receivers through three transmission lines which are connected to the respective transmitters. The serial transmission signals provided from the three transmitters are stored in memories which are connected to the respective transmitters. After all the serial transmission signals from the transmitters have been stored in the three memories, one or several data is/are loaded from each memory into an error detector so as to sequentially compare the data fetched from the three memories. Owing to this operation, which of the information transmission channels involves an error can be decided.
In the signal diagnosis of such triple information transmission system, after all the serial transmission signals have been entirely stored in the three memories, the transmission signals stored in the respective memories are read out and compared by the error detector. Therefore, the error decision of the transmission signals is late, and the rate of information processing behind the receivers becomes slow.